could a nucleus in an excited energy state or perhaps in a excited isomer be considered to be a halo nuclei for the brief time it is in the excited state?
i suppose halo nuclei are strictly speaking in their ground state though?
I recall I think that Andrea Rossi and NormanCooks theory requires the Li7 to be in its first excited state to absorbe the proton?
I wonder if the neutron or proton capture cross-section increase in size if the nuclei are in excited states.
I suppose the respective parity spin states of the particle and nucleus may also be important. But perhaps there is also a structure aspect. For example a relatively unbound neutron proton pair could maybe more easily bind to a deuteron perhaps to form a bound alpha particle? Or Inthe case of li7 as per Rossi and Cook a proton + 2 neutron triplet can more easily bind a proton perhaps?
On a separate point: Interestingly although I mentioned above Ba138 is neutron magic with82 neutrons. Ni is proton magic with 28 protons so would not really want to absorb protons. Lighter isotopes of Ni do want to absorb neutrons though. It looks like Ni is getting Protons but wants Neutrons. So if there is a process of transmutation and decay with Ni or evolution towards Ni62 perhaps it is subtly different process than the evolution of Ba to Sm but both requires similar environment with the particles approaching close enough to a nucleus for sufficient time to allow nuclear force interaction or tunneling type event or force interaction.